Apparatus for electrical treatment of gases containing corrosive material and mercury



Apl'll 21, 1931. K, l MARSHALL 1,801,515

APPARATUS FOR ELECTRICAL TREATMENT OF GASES CONTAINING CORROSIVEMATERIAL AND MERCURY Filed March 13, 1929 am aamahcl.

INVENTOR.

ATTORNEYS.

Patented Apr. 21, 1931 UNITED STATES'PATENT OFFICE K ENNETH I. MARSHALL,OF LOS AN GELES, CALIFORNIA, ASSIGNOR TO INTERNATIONAL PRECIPITATIONCOMPANY, OF LOS ANGELES, CALIFORNIA,- A CORPORATION 01 CALL PORNIAAPPARATUS FOR ELECTRICAL'TREATMENT OF GASES CONTAINING CORROSIVEMATERIAL AND MERCURY Application filed March 13, 1929. Serial No.346,808.

This invention relates to means for electrical treatment of gasescontaining corrosive material andmercury, and particularly to apparatusfor subjecting such gases to electrical action to precipitate suspendedmaterial therefrom.

The main object of the present invention is to prevent or minimize theeffect of corrosive gases on metallic electrodes used in such apparatus,by providing such electrodes with amalgamated or mercury coated surfacesadapted to resist the corrosive action. A further object of theinvention is to provide for such amalgamation or coating by operation ofthe mercury bearing gases on the electrodes.

The accompanying drawing is a vertical section of an electricalprecipitator according to my invention.

Apparatus for treatment of gases by high tension electrical field, forexample, for the purpose of precipitating suspended material therefrom,comprises in general, discharge electrode means, opposingelectrode-means, means for maintaining high potential difference betweenthe discharge and opposing electrode meansand means for passing gases tobe treated between such electrodes.

The discharge electrodes are generally of relatively small area andgreat length, being for example, wires, rods or chains, and it will beunderstood that it is necessary to make said electrodes of metal inorder to obtain In the treatment of gases bearing mercury fumes arisingfrom mercury distillation apparatus for the purpose of separation ofsuspended dust, or for the purpose of precipitation of condensed mercuryparticles, it has 1 coat them with such a metal. trode when exposed tocontact with the gases corrosive action on metal electrodes as torequire frequent replacement thereof. I have discovered that thiscorrosive action may be done away with or minimized by providing theelectrodes with an amalgamated coating or. surface adapted to resist thecorrosive action. For this purpose I prefer to make the metallicelectrodes of such an apparatus of amalgamable metal, such as copper, orto Such an elecbearing corrosive agents and mercury vapor and/or mercurycompounds, becomes automatically coated with mercury or withcopper-mercury amalgam, and the resulting coating successfully resiststhe corrosive action of the acid fumes, If desired, the electrodeshaving surfaces of amalgamable material may be coated or treated withmercury or other mercury com ound before being put into operation, butin general this is not necessary as the amal amation takes placeautomatically and rapidly in the ordinary operation of the apparatus, bythe action of the mercury and/or mercury compound present in the gasesbrought into contact with the electrodes.

In applying my invention to electrical precipitators in which thedischarge electrodes consist of wires, rods or chains, I make such.

The r sired that the collecting electrodes of an elec tricalprecipitator shall also be of metal, I prefer to also make saidcollecting electrodes of amalgamable metal, such as copper or to coatthem with such metal, the collecting electrodes, for example being madeof plates, screens or rod-curtains of copper or of iron or steel coatedwith copper.' lhe accompanying drawing illustrates conventionally anelectrical precipitator of a typical form in which the collectingelectrodes 1 and charge electrodes 2 are formed of metal, such asdescribed, having amalgamated surfaces, said precipitator having theusual gas inlet means 3, outlet means t for the cleaned gas, and means 5for receiving precipitated material, and suitable electrical connectionsindicated at 7 being provided for maintaining the high potentialdiflierence between the elec- 20 trodes. In many cases it is foundpracticable to use semi-conducting materials, such as concrete, terracotta, masonry or Wood for the collecting electrodes, it having been"found that the conductivity of such electrodes under conditionsexisting in the electrical precipitation of suspended material frommercury recovery furnaces, is sutiicient for the purpose of electricalprecipitation, it being understood that the discharge incident to theelectrical precipitation operation involves only a small current flowand the high resistance of the collecting electrode is, therefore, notinimical to successful operation. The semiconducting material specifiedare in general substantially immune to corrosive action, so that in suchcases the objects of my invention are suflicientl attained by providingthe discharge electro es alone with an amalgamated coating.

In the operation of the electrical precipitator on gases containingmercury and/or mercury compounds, the gases to be treated are passedbetween the discharge and collecting electrodes, and themetallicelectrodes being of copper or copper coated as described becomeamalgamated by the action of the mercury and/0r mercury compounds in thegases or in case the said electrodes have already been superficiallyamalgamated as described, the action of the mercury content of the gaseswill tend to reinforce the amalgamated coating or to renew it in case ofinjury thereto, so that in any case the amalgamated coating on theelectrodes is maintained in efi ective mercury coated condition duringthe operation of the apparatus, thereby preventing or minimizing thecorrosive efi'ect of the gases on, the electrodes, the effect of suchgases on the mercury coating being negligible. 6 I claim:

1. An electrical precipitator comprising discharge and collectingelectrodes, said discharge electrodes consisting of metal and thesurfaces thereof being amalgamated.

2. An electrode for electrical precipitators consisting of metal andhaving its surface

